[Openal] How to vary the speed of sound

[Chris Robinson]

On Sunday 18 May 2008 04:43:05 am wassim_belhadj at topnet.tn wrote:
> I would like to know how to vary the speed of sound using OpenAL.

The global speed of sound is defined by the attribute AL_SPEED_OF_SOUND:
alSpeedOfSound(343.3f);
speedofsound = alGetFloat(AL_SPEED_OF_SOUND);

Note that this only affects sounds playing with a doppler effect.

> For example, at a click on a button the sound is played with a  faster
> speed from the position where the action was made.

The speed of sound, however, doesn't sound like your problem here. This makes 
me think you either have a pitch set on the source, or velocities set on the 
source and/or listener (causing doppler to be applied). Or perhaps you called 
alBufferData with the incorrect frequency.

Note also that there are some issues if you're using AL_SOURCE_RELATIVE for 
the sound. It seems some implementations don't make the velocity relative, as 
defined in the 1.1 spec (particularly, the old Windows version, and by 
extension OpenAL Soft, and I think the SI). I can probably fix this for 
OpenAL Soft, but I don't know about other implementations.